Catalytic Divergent [3+3]- and [3+2]-Cycloaddition by Discrimination Between Diazo Compounds

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Cycloaddition reactions are fundamental in organic synthesis for constructing cyclic molecules.
• Developing highly selective and efficient catalytic systems for complex transformations remains a key challenge.

Purpose of the Study:

• To develop novel catalytic systems for divergent cycloaddition reactions.
• To explore the synthesis of complex heterocyclic scaffolds using enoldiazo compounds and α-diazocarboximides.

Main Methods:

• Utilized copper(I) and dirhodium(II) catalysts for divergent cycloaddition reactions.
• Employed tetrakis(acetonitrile)copper(I) tetrafluoroborate for [3+3]-cycloadditions.
• Investigated Rh2(pfb)4 and Rh2(esp)2 catalysts for regioselective [3+2]-cycloadditions.

Main Results:

• Achieved the first reported [3+3]-cycloaddition of a carbonyl ylide, yielding epoxypyrrolo[1,2-a]azepine derivatives with high yields and diastereoselectivities.
• Demonstrated regioselective [3+2]-cycloaddition pathways using dirhodium(II) catalysts, affording cyclopenta[2,3]pyrrolo[2,1-b]oxazoles with excellent stereocontrol.
• Showcased the divergent reactivity of enoldiazo compounds and α-diazocarboximides under different catalytic conditions.

Conclusions:

• Developed highly selective catalytic cycloaddition reactions for synthesizing valuable heterocyclic compounds.
• Established new synthetic routes to epoxypyrrolo[1,2-a]azepine and cyclopenta[2,3]pyrrolo[2,1-b]oxazole derivatives.
• Highlighted the versatility of copper and rhodium catalysts in controlling cycloaddition pathways and stereochemistry.